Ground anchoring system

ABSTRACT

A ground anchor comprises a generally flat anchor plate folded into a U or V-shape against a resilient bias. The resilient bias may be inherent in the folded portions of the anchor plate, or may be provided by means of auxiliary or plate springs disposed between the folded portions. In the latter, a retaining pin may secure the folded portions together while driving the plate into the ground. A release arrangement shears the pin so that the plate springs open to resist subsequent extraction.

This invention relates to a ground anchoring system of the type in whichan object is anchored to the ground by a ground anchor secured at oneend of a flexible anchor line, the other end of the line being securedto the object, and the anchor being forcibly driven into the ground by adriving tool. The system can be used underwater, for example whenanchoring mats of synthetic fronds to a river or sea bed.

It is important in such a system that the anchor should resistextraction once it has been driven into the ground. For example, wherethe anchor is in the form of a flat plate which cuts a channel whiledriving into the ground, some means for skewing the plate across thechannel is generally required or the plate will be simply pulled back upthe channel when the anchor line is tensioned.

Invariably, however, this has required the addition of fixed or movingparts, such as flaps, barbs or flukes, which project from the plate andengage the sides of the channel. Such projections necessarily complicatethe structure of the anchor and offer undesirable resistance to thepassage of the anchor when driving it into the ground.

The plate also requires some form of socket or locating pin forreceiving the driving tool, and this further increases the number ofexternal projections. Correct operation of such plates is often hamperedby soil collecting in the hinges associated with the moving parts.

It would therefore be an advantage to provide a ground anchor withoutany external projections or moving parts, but which is still capable ofresisting extraction once it has been driven into the ground.

According to the present invention, there is provided a generally flatanchor plate device folded into a U or V-shape against a resilient bias,means for releasably retaining the anchor plate device in its foldedstate while driving the plate device into the ground, and means forreleasing the retaining means so that the plate device springs open toresist subsequent extraction.

The folded anchor plate device is preferably secured to one end of aflexible anchoring line. In one embodiment, the line incorporates aground-engaging stop member spaced from the anchor plate device suchthat, when the anchor reaches a depth which brings the stop member intoengagement with the ground, further downward movement of the anchorextends the anchor line and trips the release mechanism.

In one alternative embodiment, the release mechanism is actuated by anindependent release line which extends upwardly from the anchoralongside the anchor line.

The anchor line is preferably in the form of a web, strap or tape, whichis secured independently to each of the opposed inside faces of thefolded U or V-shaped anchor plate.

A driving tool for driving the anchor downwardly into the ground ispreferably inserted between the two opposing inside faces of the foldedU or V-shaped anchor device and extends upwardly alongside the anchorline. The anchor therefore has a clean, smooth external profile with noprojections, hinges or other devices impeding the downward movement ofthe anchor into the ground. The use of a folded plate also doubles theeffective area of the anchor when the plate is sprung open.

The driving tool preferably comprises an elongate shaft attached, forexample, to a pneumatic hammer, and terminating in a device having aplurality of driving surfaces for engaging respective portions of thefolded anchor device.

The generally flat anchor plate device preferably comprises a singlecontinuous sheet or plate, and the resilient biasing force is preferablyprovided by a flat plate spring. In one embodiment the anchor sheet orplate itself forms the spring. Alternatively, an independent flat platespring is secured to the anchor sheet or plate and symmetricallydisposed about the fold line. Other forms of spring, such as a leafspring, can also be used.

The generally flat anchor plate device might alternatively comprise twoplates hinged to one another or independently connected to respectiveinside or outside faces of a flat plate spring folded into a V-shape.

In the accompanying drawings, by way of example only:

FIG. 1 is a diagrammatic front view of an anchoring system embodying theinvention;

FIG. 2 is a view similar to FIG. 1 showing operation of the releasemechanism;

FIG. 3 is a diagrammatic side view showing the anchor in its sprungopen, splayed state;

FIG. 4 is a side view of the anchor prior to folding the anchor into itsU-shaped configuration;

FIG. 5 shows the anchor of FIG. 4 folded into its U-shaped configurationand also shows the anchor line attachments and retaining mechanism;

FIG. 6 shows the anchor of FIG. 5 sprung open;

FIG. 7 shows the anchor of FIG. 4 with a driving tool inserted;

FIG. 8 is a diagrammatic front view similar to FIG. 2 but with analternative release mechanism;

FIG. 9 is a side view of the release mechanism of FIG. 8, and

FIG. 10 is a detail showing three alternative configurations for theleading edge of the anchor plate.

Referring to these drawings, a ground anchor system is illustrated inwhich an anchor plate 10 is secured to one end of a flexible anchor line11. The line 11 comprises a web or tape consisting of a woven linearcomposite.

The rectangular plate 10 is initially flat as shown in FIG. 4 but isthen tempered and folded into a U-shaped configuration about a centraltransverse fold line 12. The plate includes web attachment points 13,14, one on each of the opposing inside faces of the U-shapedconfiguration. To assist folding, some metal is preferably removed alongthe fold line to form a gulley 25 in the underside of the plate.

The plate 10 is folded into a U-shaped configuration against a resilientbias. FIGS. 5 and 6 illustrate two alternative forms of spring which maybe used to provide this bias. FIG. 5 shows a bent leaf spring 15, andFIG. 6 shows a flat plate spring 16. A further alternative would be toform the anchor plate itself as a flat metal spring, and in this case noauxiliary spring mechanism would be required. However, the thickness ofthe plate would be reduced to provide the necessary resilience, and theplate might be formed, for example, entirely of carbon steel. Theleading edge of such a plate is preferably protected by an outer coatingof high abrasion resistant synthetic material or by a preformed lightmetal plate or shield 33 bonded or otherwise secured to the main anchorplate, as shown in the three alternative configurations of FIG. 10.

The plate is retained in its U-shaped configuration against theresilient bias by a shear pin 17 which passes through both sides of theplate and through the web attachment straps 11a, 11b securedrespectively to the attachment points 13 and 14.

A bifurcated end section 19 of a driving tool spigot 18 is inserted intothe folded anchor plate 10 and straddles the shear pin 17 as shown inFIG. 1.

The web 11 incorporates an outwardly projecting web stop 20 in the formof a circular disc which prevents the web being driven any further intothe ground. Accordingly, when the anchor plate reaches the positionshown in FIG. 1, further downward movement of the driving tool 18 to theposition shown in FIG. 2 forcibly extends the web 11. As the webstretches, it exerts a force on the shear pin 17 sufficient to shear thepin so that the anchor plate springs into its splayed open positionshown in FIGS. 3 and 6 and in dashed outline in FIG. 5. This shearing ofthe pin 17 preferably occurs against the bridging portion 21 of thebifurcated end section 19 of the driving tool. Accordingly, thisbridging portion 21 might be curved oppositely to that shown in FIGS. 1and 2 so that it curves down below the upper edge of the anchor plate.As the web 11 is stretched between the attachment points 13, 14 and thepin 17, it forces the pin 17 upwardly against this bridging portion 21of the driving tool to assist the severing action.

In cases where the anchor line is substantially nonextendible, analternative form of release mechanism can be used. For example, as shownin FIGS. 8 and 9, in place of the rivet pin 17, the inside opposingfaces of the plate 10 may each be provided with a respective horizontalretaining eye 30a, 30b, the two eyes overlapping one another and theplate being held in its folded U-shaped configuration by a verticalsplit pin 31 passing through the two eyes. This locking pin may then beconnected to a release line 32 which extends upwardly alongside the web11. When the anchor plate has been driven to the required depth, therelease line 32 is pulled to remove the vertical locking pin.

If the release line 32 is secured to the inside face of the web 11, thisform of release can also be used with extendible webs, the stretching ofthe web described in the embodiment of FIG. 2 then tensioning therelease line and removing the pin 31.

As best shown in FIG. 7, each prong 22 of the bifurcated end section 19of the driving tool carries a pair of opposed shoulders 23, 24 whichbear against respective upper edges of the U-shaped plate 10. The prongs22 help to maintain alignment of the plate while the drive load isspread over the four shoulders 23, 24 and the base of the prongs whichalso engage the anchor plate along the fold line.

The above described anchor system is particularly suited for useunderwater where the anchor plate 10 is driven into a river or sea bedand the driving tool is carried by a diver. The other end of the anchorline might then be secured to a mat of synthetic fronds for creating apermanent consolidated sand bank to prevent scouring of the sea or riverbed around support structures.

I claim:
 1. A ground anchor adapted to be connected to an end of aflexible anchor line and forcibly driven into the ground, said linebeing secured to an object being anchored, said ground anchor comprisinga generally flat plate device folded into a U or V-shape against aresilient bias, a retaining arrangement connected to folded portions ofsaid folded flat plate device for releasably retaining the plate devicein the folded state while driving the anchor into the ground, and arelease arrangement connected to the flat plate device for releasing theretaining arrangement so that the plate device springs open to resistsubsequent extraction.
 2. A ground anchor according to claim 1, whereinthe release arrangement is actuated in response to a predeterminedlength of the anchor line being driven into the ground.
 3. A groundanchor according to claim 2, wherein the anchor line is extendible andcarries a ground-engaging stop member located such that, when the anchorreaches a depth which brings the stop member into engagement with theground, further downward movement of the anchor extends the anchor lineand trips the release arrangement.
 4. A ground anchor according to claim2, wherein the retaining arrangement includes a shear pin extendingthrough the anchor line.
 5. A ground anchor according to claim 1,wherein the release arrangement is actuated by an independent releaseline which extends upwardly from the plate device alongside the anchorline.
 6. A ground anchor according to claim 5, wherein the retainingarrangement includes a locking pin secured at one end of the releaseline and passing through a linkage between opposing inside faces of thefolded portions of the folded flat plate device.
 7. A ground anchoraccording to claim 1, wherein the flat plate device comprises a singlegenerally rectangular sheet transversely folded into the said U orV-shaped configuration.
 8. A ground anchor according to claim 7, furthercomprising an auxiliary spring secured to an inside face of one of thefolded portions to provide said resilient bias.
 9. A ground anchoraccording to claim 8, wherein the auxiliary spring is a flat platespring.
 10. A method of anchoring an object to a river or sea bed,comprising securing the object to one end of a flexible anchor line;securing an other end of the flexible anchor line to a generally flatanchor plate device folded into a U or V-shape against a resilient bias;inserting a driving tool between opposing inside faces of the foldedanchor plate, releasably retaining the anchor plate in its folded statewhile driving the plate into the ground, and then releasing thereleasably retained anchor plate such that the plate springs open toresist subsequent extraction.
 11. A method according to claim 10,further comprising engaging a projecting portion of the driving toolwith uppermost edges of the U or V-shaped plate when driving the plateinto the ground.
 12. A ground anchor adapted to be connected to an endof a flexible anchor line and forcibly driven into the ground, said linebeing secured to an object being anchored, said anchor device comprisinga generally flat plate device folded into a U or V-shape against aresilient bias, said resilient bias enabling folded portions defined bythe folded flat plate to spring open after the plate is driven into theground to resist subsequent extraction.
 13. The ground anchor of claim12, wherein opposed inside faces of the folded portions of the foldedflat plate are independently connected to portions of the flexibleanchor line at one of said ends.
 14. The ground anchor of claim 12,wherein said one end of the flexible anchor line is attached to bedriven into the ground together with the folded flat plate.
 15. Theground anchor of claim 12, wherein the folded portions of said foldedflat plate are connected together along a fold line portion of thefolded flat plate which forms the leading edge of the anchor as it isdriven into the ground.